As illustrated in FIG. 41, it has been hitherto suggested for a pneumatic tire to dispose a band layer g wherein low-elastic band cords made of, e.g., nylon are arranged in the circumferential direction of the tire outside a belt layer b. In recent years, as this band layer g, a band ply f has been used, the ply f being formed by winding a small-width and belt-form ply c, wherein the band cords are stretched and arranged in parallel and coated with a rubber, spirally on the outside of the belt layer. In this band layer g, the band cords arranged substantially along the equator of the tire fastens and restricts the belt layer b. It is known that this causes the suppression of a rise of ends of the belt layer b (the so-called lifting) at the time of high-speed traveling and an improvement in high-speed durability.
When such a band layer is deposited, the power of restraining the belt layer is raised up so that the rigidity of the tread face is made high. Thus, it has been made evident that, for example, road noise (noise in a car) of about 250 Hz in frequency is decreased and, depending on the arrangement of the band, transit noise (noise outside the car) is also decreased. It has been made clear that, in particular, the noise decreasing effects can be made larger by adjusting the modulus.
In other words, the band ply intends to improve the high-speed durability of the tire as described above, but it has been made evident that road noise (noise in a car), transit noise (noise outside the car), which is heard outside the car, the rolling resistance thereof, and so on change to some degree depending on the specification of the band ply, for example, the adaptation of high-modulus cords made of, for example, polyethylene naphthalate.
As this band ply, a full band ply, which covers almost all width of a belt layer, and an edge band ply, which covers only both ends of a belt layer, are known. There are pneumatic radial tires using only a full band ply, pneumatic radial tires using an edge band ply, and pneumatic radial tires using a full band ply and an edge band ply. Practical use and development of such a band ply are essential, in particular, for high performance tires.